I will be reformatting this post in the future to include all sample tests all on the same scale and compared to their native bare speaker response. For now, scan the thread, sorry.

Here is my reference speaker. This speaker has a very good frequency response and a 1500hz cross over. It's a DIY Speaker but if you'd like to know more about it, I can give you details.

This is it's frequency response. For the following measurements, I used a 4.5ms gated impulse response without any smoothing. This offers the most detailed measurements even though we're used to reading smoothed graphs.

Here is my setup. I'm using a Dayton T-amp to drive the speaker from the output on my computer. My microphone is a Behringer ECM8000 calibrated by Cross Spectrum Labs (their top level of Calibration). The mic is driven by a Blue Icicle phantom power USB preamp. Decent stuff that I feel confident using and sharing my results.The mic was centered on the tweeter and placed approximately 0.6m from the baffle.

I then streched the spandex LIGHTLY around baffle and pinned it in place. I did it lightly so that someone could read these results and feel confident that they're acoustic transparency would be equal or better.

First up, the most acoustically transparent, the Joanne's. Very thin stuff this is. Note the 2db scale. Blue is the speaker bare. Red is one layer of spandex. Green is 2 layers of spandex.

Next is Fabricland. This is the medium weight stuff.

And last is the spandex world stuff. This stuff definetely is the thickest feeling stuff.

Conclusion: The results are as expected. The heavier stuff attenuates the upper frequencies more than the thin stuff. Another thing that happns is doubling up has notable attenuation. Something of a surprise is that the back wave reflection starts to cause some suckouts in the very high frequencies. I'm speculating at this point. EQ would not be a reasonable way of fixing this because it's not consistent and the locations of any suckouts may not be the same for everyone. My data can only highlight the issue, not offer a fix.

UPDATE - Conclusion: Milliskin is the best. XD is basically equal to 2 layers of milliskin. Fabricland is very good for those living in Canada.

Thanks to all who provided samples and participated. Zheka, BlasterMaster, efaust, and all who encouraged me and added to the discussion. I am still open to accepting materials for testing. PM me for shipping details.

I layed the spandex across my screen and took some photos. Here it is with a lights turned on and the projector turned off, the camera is zoomed in a bit compared to the rest of the screen shots. The background is my screen, which is Fabric Land silver over Joanne's white. The scrap on the left is Moleskin silver matte. The scrap on the right is Joanne's white.

I used a Nikon D3000 on a tripod and kept the shutter fixed at 1/3 iirc. My beamer is a Viewsonic Pro8200 shooting from 10 feet away onto a 92" screen. I have a ton of lumen output compared to most people. Reviewing the photos, I'd say they are fairly telling of what I see in real life, except I have the advantage of having seen the difference first hand, so the differences may be more obvious to me.

My impression is the Joanne's leaks a LOT of light. Way to much. You might meed three layers to make it work. The spandex world stuff is the darkest. The Fabric Land stuff is the best imo. It's silver gives dynamite contrast, but the bright spots on the image are bright and punchy. The spandex world stuff mutes bright spots and the darks/blacks are only equal to the Fabric Land Active Wear. Combined with the AT results, the Fabric Land stuff is awesome and by far the best imo. To bad it's $27/m and only available in Canada. With a different PJ in a different room, my opinion would likely change. Fabricland white would likely suit most people better. Or maybe Joanne's white overlying spandex world grey. I dunno.

Hey Zheka. I agree that two layers of moleskin is a little to heavy. I'm personally using a layer of Joanne's under a layer of Fabricland. I should add to my OP that my measurements are unsmoothed and gated at 4.5ms. What this means is you can actually see the suck outs for what they are and how high Q thee are (how pointy they are) smoothing would cover this up. So a smoothed graph would show the same trend I have shown, but not the location and Q of the suck outs as these graphs show.

A good point about keeping some distance. I wasn't sure about how that would affect things. I went flush to the baffle to keep it consistent. I do have a before and after of a different speaker behind my screen.

The trend is more broad. But I've also mixed two materials. It may be that mixing materials is a good thing. I could investigate that.

Edit - I should note that what we hear is about 1/6th octave smoothing. But for the purposes of investigation, I've chosen a gated measurement.

If it is all possible to do so*, this testing should be repeated using the Spandex world "Light Silver Matte Milliskin. Having seen both, the "visual" difference is quite apparent, (...mush less attenuation...) and as far as acoustically speaking, the Milliskin is substantially less dense a material, so AT properties should be improved proportionately. I'd venture to say that a L-Silver Milliskin Top over a White moleskin would be better...with a twin Milliskin effort being the best.

I am about to go up into North Missouri to do a fairly large AT screen using the Light Silver Milliskin as Top and White Milliskin under-layment. Sadly though, a visual examination is all I can offer.

* I make that request because I feel that the dis allowance of effectiveness of the Spandex World material the test seems to present is too broad considering the other viable alternatives, and a good many people can benefit from more complete info. And for certain, the vast majority of wannabee DIY'er are going to have to consider a source that is readily available to them. That being said, the test as done does of course provide some essential, although somewhat constrained data.

If someone can send me about a 12 x 24" piece of anything, I can test it.

I'm not sure if you're saying the testing is unfair, misunderstood, incorrect, or what, but its certainly accurate within reasonable standards. If you mean it doesn't validate a material you have access to, then you would be correct. I think a double layer of moleskin is to much. If a lighter product is available I'd love to test it.

I should add that Joanne's may have a silver material which would be available within the US. Or a moleskin layer over a Joanne's layer would be just fine IMO.

A good point about keeping some distance. I wasn't sure about how that would affect things. I went flush to the baffle to keep it consistent. I do have a before and after of a different speaker behind my screen.

The trend is more broad. But I've also mixed two materials. It may be that mixing materials is a good thing. I could investigate that.
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I am having hard time comparing this one with the tests because the speaker is not the same and db scale is different. I think attenuation in the 6K region is still detectable but the notch up high is not obvious at all. If it is indeed a self interference notch, would not it move lower the further away the screen is?
Do you by any chance have open cell foam similar to what Geddes stuffs his waveguide with?

You're making a really good point zheka. For starters, that is a different speaker (as you said) and fabric combo (Fabricland over Joanne's, so pretty light). I'll do a couple things. I'll adjust the scale and repost that FR (frequency response). I'll then remeasure a few things now that I've gained some insight. I'll try and figure a way to offset the material a couple inches. Don't hold your breath, not sure when I'll get to this.

If someone can send me milleskin ill do it at the same time. It cost zheka something like $3 to send to me.

I think that my statement was really pretty clear about it's intended meaning. I certainly wasn't stating it was in any way unfair, misunderstood, or incorrect.....just too narrowly defining and limited in scope to be conclusive. Why stop there...the masses clamor for more.

You obviously have the tools and the talent, so why not simply request the needed "samples" from Spandex World yourself? It would be very much a credit and accomplishment that would be appreciated for quite some time by a very many people on the Forum. Quite frankly, it would probably result in this becoming an Iconic Thread.

Being able to equal or surpass the more expensive Mfg Screens with ultra low cost DIY alternatives is a DIY Screen Forum mandate. Spandex is a classic example in that regard and obvious in it's potential use. In both an aural and visual sense, it can become the essential "Turn To" for a bunch of goodly folk who can design in a "Through the Screen Sound Stage". It's obvious when dealing with a Silver color, that the degree of reflectivity is tied to the openness of the weave. Light loss is a very big issue with many AT screens, and those that do have gains above 1.0 usually suffer from Morie.

Moleskin has had all the Press, and yes I've used and suggested it. And I tried a normal "Silver" in the Milliskin and myself found the attenuation to severe to my tastes (...I am NOT an advocate of 0.85 Gain using anything....) A real shame that, seeing the latter owes nothing to coated or non-coated Cloth Screen materials, woven or perforated as far as smoothness and a total lack of Morie. I can say that only the very finest of HVLP applied coatings compare, and I do so love my HVLP. Seems that somehow the "Light Silver Matte Milliskin got left in the Moleskin's wake.

To me...the visual aspect is even more important. Many, many more people have expressed a desire to have a ultra lightweight screen to simply hang on the wall. That too has been / is a basic DIY tradition. BOC screens can, when coated, be exceptional. But the needed Frame for a 135" diagonal BOC screen is anything but lightweight. Do a 120" Spandex screen and weight tops out at 20 - 25 lbs

The right Spandex can deliver great, easier results for so many various people it's.....well, it hold great promise. And I commend your work for both it's intent and accomplishment. It's just to get to "The Truth", a few more objective samples need to be included. I sincerely hope you get inundated by enough contributions to outfit a Ski team. ....and post up an impressive test.

Ok MM. I honestly didnt understand you initial posts intent. I think the data is objective, but is only useful for the samples I have, that's right. That doesn't mean it isn't useful for someone deciding to use two layers of moleskin. I'm going to take zheka's suggestion to explore distance a little, but at this point, based on the measurements and the "feel" test holding this stuff in my hand next to the others, I'd avoid two layers of moleskin.

Based on these three materials only, if ill were in the US, I'd use A layer of Joanne's and a layer of moleskin. Bad news though, I can't find my dang receipt from Joanne's. and I know they had more than 1 type of spandex. Both were fairly thin though. When I'm back in the US ill bring my sample and try to compare in the store.

Oh and I should add that I haven't purchase any spandex world for myself cause shipping is a killer to Canada. I've found an excellent solution for myself and am doing this to help people. So if someone has a scrap they can send me for $3 or $4 that's a lot less than the $30 or $40 it would cost me to get a yard here

Great stuff tux, I had a feeling this was going to be the case, and is one of the reasons I ALMOST ordered the millskkin.
I am only going to use 1 layer of the Moleskin I bought(silver and white), and it will most likely be the white due to the fact that I prefer my whites to actually look white, and also because of light loss from the darker colors.

Thanks for the effort, much appreciated.

Why waste $ on more cheap stuff, it's like challenging a dragon with a pocket knife.

It would be interesting to see the results of different amounts of stretch. I have a layer of milliskin and one of moleskin, but each are stretched at least 25%. I know I can't perceive a difference with the speaker in front or behind, but that is a far cry from the actual results you have been able to document here. Thanks for the testing you have done.

My setup sounds great to me using two layers of moleskin, but blast it, Tux, now you've made me think that I'm probably missing something better lol. I do have to admit that I'm leaning towards ripping apart my grey over white setup and trying again with white over grey, albeit stretched much more than before. Whites aren't white, although I have some of the best blacks I've ever seen. If I'm still getting a major loss of lumens, though, I'm going to have to figure something else out. As people have said before, thanks for your efforts.

Ha, I'm causing some concern. Well before you go and rebuild your screen let me try some things. It'll take me some time. But I'll try pulling the material away a few inches and ill also try stretching it really tight.

In my own screen (measurement above) I don't have any issues. That is with much lighter material though. But it's also stretched quite a bit more. I'm sure most people's screens perform better than I've shown. I wouldn't say it's night and day better, but no one should panic

Anybody with some spare milleskin or any other interesting potential materials?

Ha, I'm causing some concern. Well before you go and rebuild your screen let me try some things. It'll take me some time. But I'll try pulling the material away a few inches and ill also try stretching it really tight.

In my own screen (measurement above) I don't have any issues. That is with much lighter material though. But it's also stretched quite a bit more. I'm sure most people's screens perform better than I've shown. I wouldn't say it's night and day better, but no one should panic

Anybody with some spare milleskin or any other interesting potential materials?

tuxedocivic, thanks for great contribution! Although I'm not interested in spandex your measurements piqued my interest. I'm in search of AT black material to cover my walls and ceiling in my HT. I don't want to drop RT60 at HF too much (I think you will understand this). The best renown material for this is devore black velvet. Some say it's AT. I though maybe you'd have it so you could perform the same test.

Tux, this is great stuff, thank you. It is great to have this info in deciding. I am just wondering, for the "average" listener, will the results you obtained be noticeable? Obviously there is loss as you so painstakingly documented, but would we notice it? Sorry if this is a silly question.

John, I almost replied to blaster master's post by saying "well if it sounds good to you...". The problem with that is it just might sound good but there is still a problem. It's like if someone said you know if you switch those component cables on your PJ for an hdmi cable you'd get 1080p and you replied nah, looks good to me. If the results I got match what others are getting on their screens (tight stretch and spaced from the speaker) then yes, this is quite audible. Most speakers need to stay within +/-3db in order to have a proper tonal balance. The double moleskin takes that way out of spec. Once I've done some more testing we should have a better idea of how severe it really is. In the mean time, anyone building a screen out of double moleskin should stretch that stuff as tight as possible. Or use 1 layer.

Thanks, great info. I have a painted screen now with black velvet tape border and some in walls (L,R and Center mounted around the screen. I have throw/screen limitations now, but when this projector goes I will upgrade. I will go for a better projector and larger screen so an AT screen would allow me to leave my speaker set-up AND get a larger screen so I am very interested in AT screen and how they involve. Thanks!

An interesting post by Seymour (sp?). I don't doubt that angle has a little to do with it, but I'm thinking its swamped by the global affect of the material. Seymour's own plots seem to show this even though he says they show it matters. His plots are very hard to read, but if I'm reading them right, the competitors screen actually has increased output at off axis angles.

Have I read this right? Wish he had gated out the room interaction and used a better frequency scale.

An interesting post by Seymour (sp?). I don't doubt that angle has a little to do with it, but I'm thinking its swamped by the global affect of the material. Seymour's own plots seem to show this even though he says they show it matters. His plots are very hard to read, but if I'm reading them right, the competitors screen actually has increased output at off axis angles.

Have I read this right? Wish he had gated out the room interaction and used a better frequency scale.

I think you are right, the perforated screen seem to show less HF attenuation at 40 degrees than at 0 or 10 degrees. I am curious why that is. One thing worth noting is that perforated screens a generally placed at least one foot away from the speakers for best result. So the whole test and comparison may not have been totally fair.

Linear frequency scale sucks. can you spot the software he used?

When we put so much emphasis on off-axis response of loudspeakers, it may be important to find screen material that does not affect it in a significant way. That's the takeaway point for me.

Hi tuxedocivic. I'm currently building a screen with Spandex World white and light silver milliskin. I'd be happy to send you a sample of either or both if you would be willing to test it. What is the minimum size you would need to stretch it around your speaker? I'm sure I'll have some left over as I bought 4 yards of each.